Import prices excluding petroleum were flat from August. Compared to September last year, they fell 1.0 percent, the largest drop since November 2009.

The report was originally scheduled for release on Oct. 10 but was delayed after the federal government was partially shut down because of a fight over the budget. The 16-day shutdown ended last Wednesday.

The general lack of imported inflation pressures against the backdrop of weak global demand should help the Federal Reserve to maintain its monthly bond purchasing program into early next year as it tries to nurse a lackluster economy back to health.

Domestic inflation is also muted and will likely stay that way for a while as demand remains tepid.

Elsewhere, imported capital goods prices were flat, as were prices for motor vehicles. Automobile prices fell 1.2 percent from a year ago, the largest year-over-year decline since records began in June 1981.